Wireless Network Scheduling Data Frames Including Physical Layer Configuration

ABSTRACT

A wireless network is disclosed in which individual wireless stations can be configured to implement any of a plurality of physical configurations including antenna configurations. Such antenna configurations may include, without limitation, multiple input multiple output (MIMO) and single input single output (SISO). Different types of MIMO configurations can also be implemented such as open loop MIMO and closed loop MIMO.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional claiming priority to thenon-provisional application Ser. No. 10/222,477 filed Aug. 16, 2002which claimed priority to provisional application Ser. No. 60/369,004,filed on Apr. 1, 2002, entitled “MIMO Enhancement Protocol Specificationfor 802.11e,” the teachings of which are incorporated herein byreference. This application also contains some subject matter that maybe somewhat related to non-provisional application Ser. No. 10/188,188,filed on Jul. 2, 2002, entitled “MAC Extensions for Smart AntennaSupport,” the teachings of which also are incorporated herein byreference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to wireless communications. Moreparticularly, the invention relates to medium access control (MAC)frames and mechanisms that permit wireless devices capable of more thanone concurrent antenna configuration to be configured for any of suchconfigurations via MAC frames sent by other wireless devices such asaccess points.

2. Background Information

Initially, computers were most typically used in a standalone manner. Itis now commonplace for computers and other types of electronic devicesto communicate with each other over networks. The ability for computersto communicate with one another has lead to the creation of smallnetworks comprising two or three computers to vast networks comprisinghundreds or even thousands of computers. Networks can be set up toprovide a wide assortment of capabilities. For example, networkedcomputers can be established to permit each computer to share acentralized mass storage device or printer. Further, networks enableelectronic mail and numerous other types of services. Networks have beenestablished in a wired configuration in which each entity on the networkhas a direct physical electrical connection to the network. Morerecently, advances in wireless technology has made it possible fornetwork devices to communicate with others via radio frequency (RF) orother types of wireless media.

To implement a wireless network, each device (computer, access point,etc.) includes one or more antennas through which data is transmitted orreceived. One type of antenna configuration is referred to as singleinput, single output (SISO) and is depicted conceptually in FIG. 1. Twonetwork stations 10 and 12 are shown in communication with each other.The stations could be computers, access points, and the like. In a SISOconfiguration, each station 10 and 12 includes a single antenna 14 and16, respectively. Each station actually may have multiple antennas, butonly one is used at a time. Data is communicated between the stations10, 12 in an exchange sequence via the single wireless link 18.

An exemplary exchange sequence is illustrated in FIG. 2. One of thestations 10, 12 sends a data frame 20 to the other station whichresponds with an acknowledgment frame 22. The data frame may include apreamble 24, a header 26 and a data payload 28. Similarly, theacknowledgment frame 22 includes a preamble 30, a header 32 and a datapayload 34. The data frame conveys data to the receiving station and theacknowledgment frame lets the sending station know that the data framewas correctly received. If the data frame was not correctly received(e.g., due to noise or interference), the sending station may resend thedata frame.

The total elapsed time required for the data frame 20 and subsequentacknowledgment frame 22 to be transmitted in a SISO antennaconfiguration is shown in FIG. 2 as time T_(SISO). To a certain extent,the information contained in data frame 20 may be transmitted in lesstime using a multiple input, multiple output (MIMO) configuration suchas that shown in FIG. 3. As shown, stations 10, 12 each includes a pairof antennas that communicate with the pair antennas on the otherstation. Thus, for example, antenna 40 can communicate with antennas 44and 46 and antenna 42 also can communicate with antennas 44 and 46,thereby establishing four simultaneously available communication links48, 50, 51 and 53 between stations 10 and 12. This type of MIMOconfiguration is referred to as a “2×2” MIMO configuration, and othertypes of MIMO configurations exist in which more than two antennas ateach station are implemented such as “4×4” MIMO, etc.

The advantage of a MIMO antenna configuration is illustrated with regardto FIGS. 4 a-4 c. FIG. 4 a simply repeats the SISO frame exchangesequence from FIG. 2. As noted above, the time required to transfer thedata and acknowledgment frames is T_(SISO). FIGS. 4 b and 4 c depict theframe exchange sequence using the 2×2 MIMO antenna configuration of FIG.3. With MIMO, the bit stream can be broken into two parts and the partscan then be transmitted simultaneously via the four communication links48, 50, 51 and 53. Thus, the overall time required to transfer the sameinformation is advantageously reduced. In FIG. 4 c, the total time isshown as T_(MIMO), which is less than T_(SISO). The time savings largelycomes from being able to divide the data payload 28 of the data frame 24into two smaller fields 52 and 54. Various techniques are known fordoing this such as putting all of the even bits of data field 28 intofield 52 and the odd bits into field 54. At the receiving station, thedata parts 52 and 54 then can be reassembled into a single data payload.Although the data field can be broken up and transmitted concurrently,the preamble and header fields 24 and 26 cannot be broken apart.Nevertheless, significant time is saved in transmitting the frame in aMIMO configuration as opposed to a legacy SISO configuration.

It is generally desirable to provide wireless networks that can beconfigured as flexibly as possible. For example, it might be desired forsome stations to be SISO only while other stations are capable of MIMOcommunications, thereby implementing a mixed MIMO/SISO wireless network.Further still, of the MIMO stations, it might be desirable for somestations to be configured as 2×2 MIMO, while other MIMO stations are 4×4MIMO. It might also be desirable for some stations to reconfigurethemselves for different types of MIMO or SISO configurations duringoperation as they communicate with other stations on the network. Ingeneral, MIMO stations may not know in advance which antennaconfiguration should be used to receive an incoming frame from the airor to transmit a frame to another station or even which operational mode(e.g., open loop MIMO, close loop MIMO, beam forming, etc.) to use.Moreover, a solution to this problem is desirable.

BRIEF SUMMARY OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The preferred embodiments of the present invention solve the problemsnoted above by a wireless network in which individual wireless stationscan be configured to implement any of a plurality of physicalconfigurations including antenna configurations. Such antennaconfigurations may include, without limitation, multiple input multipleoutput (MIMO) and single input single output (SISO). Different types ofMIMO configurations can also be implemented such as open loop MIMO andclosed loop MIMO.

In accordance with a preferred embodiment of the invention, anotherstation (e.g., an access point) configures a station for the desiredphysical configuration by forming and sending a communication frame tothe station. The frame includes at least one bit in which the physicalconfiguration information is encoded. The frame may comprise an existingpolling frame type or a non-polling frame type. As a polling frame, theconfiguration information is encoded in a pair of bits that are used forother purposes in other frame types. Preferably, the polling frame isone of a plurality of types of quality of service (QoS) polling framesand the bits used to encode the configuration information otherwise areused to encode frame retry and power management information. As anon-polling frame, the frame preferably comprises one of a plurality oftypes of QoS non-polling frames and the configuration information isencoded in a field that is otherwise used to encode transmissionopportunity time periods in other contexts.

In accordance with one aspect of the invention, a method is disclosed ofimplementing communication frames in a wireless network having aplurality of wireless devices in which some of the devices are capableof different physical layer configurations than other of said devices.This method comprises forming a polling frame including at least one bitin which physical layer configuration information is encoded, theconfiguration information being capable of specifying whether a SISOantenna configuration is to be used or a MIMO antenna configuration isto be used. The method further includes transmitting the polling frameto a receiving device for decoding by the receiving device andconfiguring a physical layer of the receiving device in accordance withthe physical layer configuration information contained in the pollingframe, wherein the polling frame also causes the receiving device todetermine whether it has information to return.

In accordance with another aspect of the invention, a method is alsodisclosed of implementing communication frames in a wireless networkhaving a plurality of wireless devices in which some of the devices arecapable of different physical layer configurations than other of saiddevices. The method includes forming a non-polling frame including atleast one bit in which physical layer configuration information isencoded, the configuration information being capable of specifyingwhether a SISO antenna configuration is to be used or a MIMO antennaconfiguration is to be used, transmitting the non-polling frame to areceiving device for decoding by the receiving device, and configuring aphysical layer of the receiving device in accordance with the physicallayer configuration information contained in the non-polling frame.

In yet another embodiment, a method is disclosed of coordinating thebehavior of a plurality of wireless devices in a wireless network. Themethod comprises forming a frame to a wireless receiving device tospecify the antenna configuration that the receiving device is to usefor a subsequent communication, sending the frame to the receivingdevice, receiving the frame by the receiving device, decoding the frame,and configuring the receiving device to comport with the antennaconfiguration specified by the frame.

In yet other embodiments, access points and wireless stations aredescribed which are used in accordance with the methods describedherein. The preferred embodiments permit a mix wireless network to beimplemented which includes both legacy SISO-only stations and stationscapable of either SISO or MIMO configurations. The preferred embodimentsefficiently coordinates the behavior of such devices to permit bothtypes of antenna configurations to be used during run-time operation.

These and other aspects and benefits of the preferred embodiments of thepresent invention will become apparent upon analyzing the drawings,detailed description and claims, which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of theinvention, reference will now be made to the accompanying drawings inwhich:

FIG. 1 shows two wireless devices communicating with each other using asingle input, single output (SISO) antenna configuration;

FIG. 2 shows a timing sequence associated with the SISO configuration;

FIG. 3 shows the wireless devices of FIG. 1 communicating with eachother using a multiple input, multiple output (MIMO) antennaconfiguration;

FIGS. 4 a-4 c show timing sequences associated with the SISO and MIMOantenna configurations of FIGS. 1 and 3;

FIG. 5 shows a system diagram of a pair of wireless stations;

FIG. 6 shows an exemplary wireless network comprising a plurality ofstations and an access point;

FIG. 7 shows an IEEE 802.11e quality of service (QoS) frame which can beused to encode physical layer configuration information;

FIG. 8 shows one embodiment of the invention in which the configurationinformation is encoded in a frame control field included in the frame ofFIG. 7; and

FIG. 9 shows another embodiment in which the configuration informationis encoded in a QoS control field included in the frame of FIG. 7.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. As one skilled in the art willappreciate, manufacturers and suppliers of wireless technology may referto components and sub-components by different names. This document doesnot intend to distinguish between components that differ in name but notfunction. In the following discussion and in the claims, the terms“including” and “comprising” are used in an open-ended fashion, and thusshould be interpreted to mean “including, but not limited to . . . ”.Also, the term “couple” or “couples” is intended to mean either a director indirect electrical or wireless connection. Thus, if a first devicecouples to a second device, that connection may be through a directelectrical connection, or through an indirect electrical or wirelessconnection via other devices and connections. The term “frame” refers toa basic communication structure which includes overhead information anddata information. Unless otherwise stated, the terms “station” and“device” generally refer to wireless stations (WSTAs) and access points(APs). To the extent that any term is not specially defined in thisspecification, the intent is that the term is to be given its plain andordinary meaning.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the preferred embodiment of the invention, a wirelessnetwork is implemented which includes a plurality of wireless stations(both access points and non-access point stations). The antennaconfiguration of at least some of the stations is capable of beingconfigured in any one of a plurality of configurations. The network mayinclude other stations that are not capable of being so configured. Forexample, some of the stations may be capable of SISO and MIMO antennaconfigurations while other station have legacy only SISO antennaconfigurations. The preferred embodiment permits such disparate (i.e.,incompatible) type of antenna configurations to be implemented amongstations operable within the same wireless network. It should be furtherunderstood that in addition to, or instead of, the antenna subsystems ofthe stations being configurable, other aspects of the interface betweenthe station and the wireless medium may also be configurable.

The preferred embodiments of the present invention will be describedbelow in the context of the 802.11 family of wireless standards. The802.11 standard is formally known as the “ISO/IEC 8802-11 InternationalStandard (ANSI/IEEE Std 802.11)” referred to herein as the “802.11standard” for sake of convenience and incorporated herein by reference.It provides wireless medium access control (MAC) and physical layer(PHY) specifications. The 802.11e/D2.0a draft standard, incorporatedherein by reference, defines, on the basis of the 802.11 standard,Medium Access Control (MAC) enhancements for quality of service (QoS).QoS generally refers to a set of services which permits multipleapplications to run concurrently with the network infrastructuretreating each application differently in terms of latency, bandwidth,priority, etc. QoS permits multiple applications to run with a totalbandwidth that may otherwise not be enough to accommodate the needs ofthe applications. QoS permits, for example, a more latency-intolerantapplication to be run in a way that acknowledges and addresses thespecial latency requirements of that application relative to otherapplications. In general, network resources are allocated in a way thatconsiders an special needs of the applications.

Referring to FIG. 5, a pair of wireless devices (also called “stations”)100 and 102 are shown comprising a wireless network 90. Although onlytwo stations are shown in wireless network 90, in general the networkcan include more than two stations. Each station 100, 102 comprises hostlogic 104 (e.g., notebook computer, handheld computer, PDA, etc.) whichcommunicates with another station via a wireless medium 112 using a MACsublayer 106 and a PHY layer 108. The MAC sublayer 106 provides avariety of functions and services to facilitate effective wirelesscommunications between stations. Examples of such services include dataframe transmission and reception, security, and others. The host 104uses these services to effectuate communications across the wirelessmedium 112. The PHY layer 108 provides an interface between the MAClayer 106 and the wireless medium and, as such, couples to one or moreantennas 110. MAC and PHY layers are well known in the art and aredescribed in greater detail in the 802.11 standard.

The currently adopted 802.11 standard defines a structure for variousframe types such as control frames, data frames, and management frames.The discussion which follows describes various modifications to the802.11 frame structure to include PHY configuration (e.g., MIMO, legacySISO, etc) information when scheduling communications between wirelessstations and/or access points. The preferred improvements describedbelow have been made to existing frame structures so as to be able touse existing implementations as much as possible, thereby minimizingdevelopment time and cost. Further, the approach taken in the preferredembodiment in using existing frame types facilitates backwardcompatibility. Implementing such features in 802.11-compliant devicesrequires several variations from the currently adopted standard. Thesevariations have been implemented in the following discussion andassociated figures. It should be understood, however, that the scope ofthis disclosure and the claims that follow need not be limited to the802.11 context.

In the context of 802.11, however, data frames are also referred to asMAC protocol data units (MPDUs). An MPDU generally comprises a MACheader, a data portion, and a frame check sequence (FCS) field. The PHYlayer may add on a PHY preamble and a PHY header as described above. Thedata field contains a MAC service data unit (MSDU) or a fragmentthereof. Based on network activity, a station's MAC 106 may beprogrammed to fragment MSDUs in excess of a given length. Each fragmentis transmitted in a separate frame with its own MAC header and FCSinformation as well as its own PHY header and preamble.

Referring to FIG. 6 for continued context, a wireless network comprisesa plurality of stations 142-148, designated in FIG. 6 as StationA-Station D, respectively. The network also includes an access point(AP) 140 which provides connectivity to a wire- or/and wireline-linkeddistribution system. The AP 140 further contains a “coordinator” 149which preferably performs bandwidth management and scheduling on thewireless medium. The coordinator 149 may be a so-called “hybrid”coordinator currently being proposed for the 802.11e/D2.0a draftstandard.

The preferred embodiment of the invention provides the ability toconfigure the PHY configuration of a wireless station to implementeither a legacy (SISO) or MIMO antenna configuration. The 802.11standard includes a number of control, management and data frames someof which are used to coordinate the schedule for stations and accesspoints to communicate with one another. In accordance with the preferredembodiment, some of these scheduling-oriented message frames aremodified as described below, not only to schedule communications, butalso to specify the PHY configuration to use during the communication.

It has been observed that certain bits in the MAC header are not usedwhen forming QoS data frames. Some, or all, of these bits are normallyused to perform certain functions, but are required to be set to certainpredetermined values or are unused in QoS data frames. Consequently,these bits can be used in a different way and, more specifically, toencode PHY configuration information, including MIMO-related detail.FIG. 7 shows a QoS MAC frame 150. As shown, frame 150 comports withconventional 802.11 frame protocol in that it contains a MAC header 148,a frame body 168 and a frame check sequence (FCS) 170. The FCS 170enables error detection and is implemented in accordance withconventional 802.11 protocol. Header 148 preferably includes a framecontrol field 152, a duration/ID field 154, four address fields 156,158, 160 and 164, a sequence control field 162, and a QoS control field166.

The frame control field 152 specifies various pieces of information suchas the frame type and frame subtype destination address and will bedescribed in further detail below with regard to FIG. 8. The duration/IDfield is 16 bits in length and varies with frame type and subtype,superframe period and QoS capabilities of the sending station. In someframe types and subtypes, the duration/ID field carries the associationidentity (AID) of the station that transmitted the frame, while in otherframe types, the duration/ID field carries a duration value that isindicative of the remaining number of microseconds of a transmissionopportunity. The four address fields are generally used to indicate thebasic service set identification (BSSID), source address (SA),destination address (DA), transmitting station address (TA) andreceiving station address (RA) and are encoded in different waysdepending on frame type. The sequence control field 162 generallycomprises a sequence number and a fragment number. The sequence numberuniquely identifies an MSDU and the fragment number identifies asub-part or fragment of an MSDU. The QoS control field 166 preferably isa 16-bit field that identifies the traffic category or traffic stream towhich the frame belongs and various other QoS-related information aboutthe frame that varies by frame type and subtype. The frame body 168represents the data payload of the frame and is used to store whateverdata is desired to be transmitted.

Referring now to FIG. 8, the bits comprising frame control field 152 areshown in greater detail. The control field preferably includes aprotocol version field 172, type and subtype fields 174 and 176, TO andFROM DS bits 178, 180, a more fragment bit 182, retry and powermanagement bits 184 and 186, a more data bit 188, a Wired EquivalentPrivacy (WEP) bit 190 and a forward error correction (FEC) bit 192. Thenumbers along the bottom of the frame control specify the bit numbers.The protocol version field 172 is used to indicate the version of thestandard being implemented. The type and subtype fields 174 and 176(bits 2-3 and 4-7, respectively) dictate the frame functionality andpurpose. The TO and FROM DS bits 178, 180 indicate whether the frame isdestined for the distribution system (DS) or is exiting the DS. The DSinterconnects the various access points and other equipment necessary toimplement a wireless network. The more fragment bit 182 specifieswhether there are more fragments associated with the current MSDU tofollow. The more data bit 188 specifies whether more MSDUs are bufferedfor the addressed station at an access point (AP) after the transmissionof this frame. Bits 11 and 12 include the retry 184 and power management186 bits and will be addressed in more detail below. The WEP bit 190indicates whether the frame body contains information that has beenprocessed by the WEP algorithm which is an 802.11 specifiedcryptographic confidentiality algorithm. Finally, the FEC bit 192 can beset to enable forward error correction as is commonly understood.

As noted above, the proposed QoS enhancements to the 802.11e MACstandard provides an enhanced set of functions, formats, frame exchangesequences and managed objects to support handling multiple applicationseach having different resource needs. The QoS enhancements include, inpart, a set of eight QoS-related data frames. These frames are listedbelow in Table I along with the subtype bit values associated with eachframe. The two type bits 3 and 2 preferably are set to ‘1’ and ‘0’,respectively, for all of the frame types listed in Table I to indicatethe frames are all data frames. The subtype bits 7-4 differentiate onetype of data frame from another and thus each QoS-related data frameshave unique subtype values. TABLE I QoS Data Frames Subtype (bits FrameName 7654) Description QoS Data 1000 Transmits Data QoS Data + CF-Ack1001 Transmits data and acknowledges previous frame QoS Data + CF-Poll1010 Transmits data and polls device QoS Data + CF-Ack + 1011 Transmitsdata and acknowledgment CF-Poll and polls device QoS Null (no data) 1100QoS CF-Ack (no data) 1101 Transmits acknowledgment without data QoSCF-Poll (no data) 1110 Polls device without transmitting data QoSCF-Ack + CF-Poll 1111 Transmits acknowledgment and (no data) pollsdevice without data

In accordance with one embodiment of the invention, PHY configurationinformation is encoded in the QoS data poll frames which are used by thecoordinator 149 in granting contention-free transmission opportunities(TXOPs) to QoS-capable wireless stations (QSTAs). Further, it should beunderstood that the TXOP can also be granted during a contention periodand thus the preferred embodiment applies to contention periods as well.Such data poll frames are generally referred to as the QoS Poll subtypeframes and include the QoS CF-Poll (no data), QoS CF-Ack+CF-Poll (nodata), QoS Data+CF-Poll, and QoS Data+CF-Ack+CF-Poll frames.

Referring again to FIG. 8, the retry bit 184 (bit number 11) is set to avalue of 1, as dictated by the 802.11e standard, to indicate that thecurrent frame contains a retransmission of an earlier frame (that, forexample, was not received due to a transmission error). The 802.11estandard further specifies that the retry bit should be set to a valueof 0 for all other frames. The 802.11e standard further specifies thatthe power management bit 186 (bit number 12) is used to encode the powermanagement mode of the station. The standard states that the value ofthis field should remain constant in each frame from a particularstation within a frame exchange sequence. The value indicates the modein which the station will be after the successful completion of theframe exchange sequence.

It has been determined that that the retry and power management bits(bits 11 and 12) are not used in the QoS poll subtype frames. As such,and in accordance with the preferred embodiment, the retry and powermanagement bits are combined into a single field and used to encode PHYconfiguration information. Thus, the preferred embodiment of theinvention uses the retry bit and power management bit in the QoS pollsubtype frames contrary to their prescribed usage, although such bitsare still used for their stated purpose (retry, power management) inother types of frames. Any one of a variety of encoding methodologiescan be used and exactly what PHY configuration information is encodedcan be determined by the individual designer. One exemplary encodingscheme is shown in Table II below. TABLE II PHY Configuration EncodingBit 11 Bit 12 (previously Retry) (previously Pwr Mgt) PHY Configuration0 0 Legacy MIMO 0 1 1 0 Closed loop MIMO 1 1 Open loop MIMO

In this way, a station can be polled and the polling frame alsospecifies the PHY configuration that should be implemented by the polledstation (i.e., the station receiving the QoS poll subtype frame) for afuture frame communication. The polled station thus is requested torespond with an acknowledgment or data, if present, using the specifiedPHY configuration. If the polled station has MIMO capability, thepolling station can command the polled station to respond with its MIMOcapability. The polled station implements the specified PHYconfiguration when transmitting frames to the station whose MAC addressmatches the receive address which preferably is encoded into address 4field 164. The QoS control field, which will be described in more detailbelow, includes a transmission opportunity (TXOP) field which specifiesa value that is indicative of the amount of time a polled station has tosend its frames in response to the polling frame. The polled stationthus may send frames to other stations during this TXOP time periodusing the PHY configuration specified by bits 11 and 12 of the framecontrol field. The polled station may send frames to stations other thanthe station specified by address 4 using the legacy PHY configuration(i.e., SISO) and subject to the specified TXOP limit. This embodimentprovides a mechanism to inform receiving stations of the PHYconfiguration to be tuned to in receiving frames in the specified timeintervals. It applies to contention-free transmission in both thecontention free period (CFP) and contention period (CP) which areperiods well known to those of ordinary skill in the art.

In accordance with another embodiment of the invention, an alternativemethod is used to convey PHY configuration information to a receivingstation during the burst of data transmissions within a given TXOP. Thisalternative embodiment encodes PHY configuration information into theQoS control field 166 (FIG. 7) during QoS data non-poll frames.Referring now to FIG. 9, the QoS control field 166 includes a trafficidentifier (TID) 200, an FEC bit 202, an ACK field 204, a reserved/morebit 206, and a TXOP limit/queue size field 208.

In QoS poll subtype frames, as discussed above, the TXOP limit/queuesize field 200 specifies the time duration in which frame exchanges maybe initiated by the polled station. In QoS data subtype framescontaining no CF-Poll functionality (i.e., QoS Data, QoS Data+CF-Ack,QoS Null (no data), and QoS CF-Ack (no data)) that are transmitted bythe hybrid coordinator, the TXOP limit/queue size subfield is reserved.In accordance with the 802.11e standard, QSTAs set this field to 0 attransmission and ignore this field upon reception. In QoS data subtypeframes containing no CF-Poll functionality that are transmitted by awireless QSTA (i.e., a non-HC QSTA), the TXOP limit/queue size fieldspecifies the amount of traffic buffered for an outgoing trafficcategory or traffic stream as specified by the TID field 208 after thewireless QSTA transmits the frame indicating the queue size.

The FEC bit 202, together with the other FEC bit 192 in the framecontrol field 150, indicates whether the frame is FEC encoded at the MACsublayer. The ACK field 206 defines the acknowledgment policy for theframe, indicating whether an immediate acknowledgment, a subsequentburst acknowledgment, or no acknowledgment is to be returned for theframe. The TID field 200 identifies the traffic category or trafficstream to which the data contained or indicated in the frame belongs.

As indicated above, bit 206 in the QoS control field 166 shown in FIG. 9is currently reserved with regard to QoS data non-poll frames. Inaccordance with the preferred embodiment, however, this bit is used toindicate that another frame is to be transmitted from the sametransmitting station to the same receiving station in at least threesituations, namely:

-   -   (1) after a predetermined period of time following the current        frame if no immediate acknowledgment is expected,    -   (2) after a predetermined period of time following the immediate        acknowledgment to the current frame if an immediate        acknowledgment is expected, or    -   (3) after a predetermined period of time following a burst        acknowledgment to the current and previous frames if a burst        acknowledgment request and a burst acknowledgment are to be        expected after the current frame (burst acknowledgment is        described in detail in copending application entitled “A Method        and System for Group Transmission and Acknowledgment”,        incorporated herein by reference).

Preferably, the bits in field 208 (TXOP limit/queue size) of a QoS datanon-poll frame are set to a non-zero value to encode the PHYconfiguration including the transmit antenna configuration such as SISO,MIMO, and the like, that is to be used in transmitting the next framefrom this station if the reserved bit 206 in the QoS control field 160is set to a value of 1. Alternatively, the field 208 is set inaccordance with the 802.11e standard if bit 206 in the QoS control fieldof the current frame is set to 0.

The setting of the two subfields in the QoS control field 166 in QoSdata non-poll frames enables the transmitting station to inform thereceiving station of the PHY configuration to be used for the next framebetween the two stations. This feature may be used with bothcontention-free and contention-based access.

Moreover, the embodiments described above incorporate MIMO antennaconfiguration capabilities into the 802.11e MAC specification withrelatively minimal redesign. The embodiments are modifications tocurrently existing frame types.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

1-17. (canceled)
 18. A wireless station usable to communicate across awireless network, comprising: a host device; a medium access control(MAC) sublayer coupled to said host device; a physical layer coupled tosaid MAC sublayer; wherein said physical layer contains a plurality ofantennas and is configurable to communicate with other stations oraccess points on said network using any of a plurality of antennaconfigurations selected from the group consisting of multiple inputmultiple output (MIMO) and single input single output (SISO); and acoordinator to specify the physical configuration to be used duringcommunication.
 19. A wireless station usable to communicate across awireless network, comprising: a host device; a medium access control(MAC) sublayer coupled to said host device; a physical layer coupled tosaid MAC sublayer; wherein said physical layer contains a plurality ofantennas and is configurable to communicate with other stations oraccess points on said network using any of a plurality of antennaconfigurations selected from the group consisting of multiple inputmultiple output (MIMO) and single input single output (SISO); a receiverto receive a frame from the wireless network in which an antennaconfiguration is encoded and configures itself to comport with saidantenna configuration; and a coordinator to decode said frame andconfigure said physical layer to comport with said antenna configurationused for communication.
 20. (canceled)
 21. The station of claim 18wherein said antenna configuration comprises a configuration selectedfrom the group consisting of open loop multiple input multiple output(MIMO), closed loop MIMO, and single input single output-(SISO).
 22. Amethod for providing configuration information in a communicationsystem, said method comprising: forming a polling frame including atleast one bit in which physical layer configuration information isencoded, said configuration information being capable of specifyingwhether a single input single output (SISO) antenna configuration is tobe used communication or a multiple input multiple output (MIMO) antennaconfiguration is to be used for communication; and transmitting saidpolling frame to a receiving device for decoding by said receivingdevice and configuration of a physical layer of said receiving device inaccordance with the physical layer configuration information containedin the polling frame.
 23. The method of claim 22 wherein the pollingframe includes more than one bit in which the physical configurationinformation is encoded.
 24. The method of claim 22 wherein the pollingframe includes two bits in which the physical configuration informationis encoded.
 25. The method of claim 24 wherein the two bits are used toencode retry and power management information in non-polling frames. 26.The method of claim 22 wherein the at least one bit in which thephysical layer configuration information is encoded is used for apurpose other than to encode physical layer configuration information innon-polling frames.
 27. The method of claim 22 wherein the configurationinformation specifies whether closed loop MIMO, open loop MIMO or SISOis to be used.
 28. A method for providing configuration information in acommunication system, said method comprising: forming a non-pollingframe including at least one bit in which physical layer configurationinformation is encoded, said configuration information specifies whethera single input single output (SISO) antenna configuration is to be usedfor communication or a multiple input multiple output (MIMO) antennaconfiguration is to be used; and transmitting said non-polling frame toa receiving device for decoding by said receiving device andconfiguration of a physical layer of said receiving device in accordancewith the physical layer configuration information contained in thenon-polling frame.
 29. The method of claim 28 wherein the at least onebit comprises a plurality of bits that are also used to encode a valuethat is indicative of a transmission opportunity time period.
 30. Themethod of claim 28 wherein forming also includes forming the non-pollingframe to include a more bit that specifies whether a subsequent frame ofdata is to follow the current non-polling frame.
 31. A method ofcoordinating the behavior of a plurality of wireless devices in awireless network, comprising: forming a frame to a wireless receivingdevice to specify the antenna configuration that the receiving device isto use for a subsequent communication; and sending said frame to saidreceiving device for configuration of said receiving device to comportwith the antenna configuration specified by said frame.
 32. The methodof claim 31 wherein said antenna configuration comprises a configurationselected from the group consisting of multiple input multiple output(MIMO) and single input single output (SISO).
 33. The method of claim 31wherein said antenna configuration comprises a configuration selectedfrom the group consisting of open loop multiple input multiple output(MIMO), closed loop MIMO, and single input single output (SISO).
 34. Amethod of configuring a wireless device in a communication system, saidmethod comprising: receiving a polling frame including at least one bitin which physical layer configuration information is encoded, saidconfiguration information being capable of specifying whether a singleinput single output (SISO) antenna configuration is to be used forcommunication or a multiple input multiple output (MIMO) antennaconfiguration is to be used for communication; decoding the pollingframe; and configuring a physical layer of said receiving device inaccordance with the physical layer configuration information containedin the polling frame; wherein said polling frame also causes thereceiving device to determine whether it has information to return. 35.The method of claim 34 wherein the polling frame includes more than onebit in which the physical configuration information is encoded.
 36. Themethod of claim 34 wherein the polling frame includes two bits in whichthe physical configuration information is encoded.
 37. The method ofclaim 36 wherein the two bits are used to encode retry and powermanagement information in non-polling frames.
 38. The method of claim 34wherein the at least one bit in which the physical layer configurationinformation is encoded is used for a purpose other than to encodephysical layer configuration information in non-polling frames.
 39. Themethod of claim 34 wherein the configuration information specifieswhether closed loop MIMO, open loop MIMO or SISO is to be used.
 40. Amethod of configuring a wireless device in a communication system, saidmethod comprising: receiving a non-polling frame including at least onebit in which physical layer configuration information is encoded, saidconfiguration information specifies whether a single input single output(SISO) antenna configuration is to be used for communication or amultiple input multiple output (MIMO) antenna configuration is to beused for communication; decoding said non-polling; and configuring aphysical layer of said receiving device in accordance with the physicallayer configuration information contained in the non-polling frame. 41.The method of claim 40 wherein the at least one bit comprises aplurality of bits that are also used to encode a value that isindicative of a transmission opportunity time period.
 42. The method ofclaim 40 wherein the non-polling frame also includes a more bit thatspecifies whether a subsequent frame of data is to follow the currentnon-polling frame.
 43. The method of claim 42 wherein configuring isperformed if said more bit is set to indicate that a subsequent frame ofdata is to follow the current non-polling frame.
 44. A method ofconfiguring a wireless device in a communication system with a pluralityof transmission devices, wherein some of said transmission devices haveantenna configurations than other of said transmission devices,comprising: receiving a frame by said wireless receiving device tospecify the antenna configuration that the receiving device is to usefor a subsequent communication; decoding said frame; and configuringsaid receiving device to comport with the antenna configurationspecified by said frame.
 45. The method of claim 44 wherein said antennaconfiguration comprises a configuration selected from the groupconsisting of multiple input multiple output (MIMO) and single inputsingle output (SISO).
 46. The method of claim 44 wherein said antennaconfiguration comprises a configuration selected from the groupconsisting of open loop multiple input multiple output (MIMO), closedloop MIMO, and single input single output (SISO).
 47. A polling framefor configuring a wireless device in a communication system, saidpolling frame including at least one bit in which physical layerconfiguration information is encoded, said configuration informationbeing capable of specifying whether a single input single output (SISO)antenna configuration is to be used for communication or a multipleinput multiple output (MIMO) antenna configuration is to be used forcommunication.
 48. The polling frame of claim 47 wherein the pollingframe includes more than one bit in which the physical configurationinformation is encoded.
 49. The polling frame of claim 47 wherein thepolling frame includes two bits in which the physical configurationinformation is encoded.
 50. The polling frame of claim 49 wherein thetwo bits are used to encode retry and power management information innon-polling frames.
 51. The polling frame of claim 47 wherein the atleast one bit in which the physical layer configuration information isencoded is used for a purpose other than to encode physical layerconfiguration information in non-polling frames.
 52. A non-polling framefor configuring a wireless device in a communication system, saidnon-polling frame including at least one bit in which physical layerconfiguration information is encoded, said configuration informationspecifies whether a single input single output (SISO) antennaconfiguration is to be used for communication or a multiple inputmultiple output (MIMO) antenna configuration is to be used forcommunication.
 53. The non-polling frame of claim 52 wherein the atleast one bit comprises a plurality of bits that are also used to encodea value that is indicative of a transmission opportunity time period.54. The non-polling frame of claim 52 wherein the non-polling frame alsoincludes a more bit that specifies whether a subsequent frame of data isto follow the current non-polling frame.